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Return to BlogSound Meter with Piezoelectric Feature
Posted Feb 02, 2012 at 3:14 pm
Figure 1
The sound meter was built with piezoelectric buzzer in reverse, as a microphone which makes a single transistor amplifier demonstrate its functionality. This leads the piezoelectric element to make the signals large enough to be read by the analog to digital converter (ADC) of the microcontroller.
A bright red LED marquee is used for the sound meter since it has to be visible in a big room. A single ATmega168 microcontroller is used to control the all the 120 high-intensity red LEDs. There are versions where the LCD screen is running 20X4 characters which can be built separately from the LED array. The minimum and maximum analog-to-digital samples during each period of measurement were some of the debugging information that is provided.
There are two less columns of the LED array since one of the pins was required for the ADC. The code was made much simpler while the sound meter does not need to take text from the computer. The movement of the text was made sideways by rotating the LED marquee to 90 degrees so that the advancement of the bars would go the same way was as the noise level.
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